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28 Jan 2018, 22:35

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25% (medium)

Question Stats:

76%(01:34) correct 24%(01:41) wrong based on 83 sessions

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Bowl X has 4 cards in it, numbered 1 - 4. Bowl Y has 5 cards in it, numbered 5 - 9. What is the probability that the sum of a card pulled randomly from Bowl X and a card pulled randomly from Bowl Y will equal 8?

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13 Feb 2018, 09:55

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Bunuel wrote:

Bowl X has 4 cards in it, numbered 1 - 4. Bowl Y has 5 cards in it, numbered 5 - 9. What is the probability that the sum of a card pulled randomly from Bowl X and a card pulled randomly from Bowl Y will equal 8?

A. 1/20B. 1/10C. 3/20D. 2/16E. 3/16

NOTE: In order to get a sum of 8, the card selected from Bowl X must be 1, 2 or 3.Here's why: Cards 1, 2 and 3 all have corresponding cards in Bowl Y that add to get 8 (i.e., 1+7 = 8, 2+6 = 8 and 3+5 = 8)However, card 4 (from Bowl X) does NOT have a corresponding card in Bowl Y that add to get 8.

So P(sum is 8) = P(card selected from Bowl X is 1, 2 or 3 AND card selected from Bowl Y is the one card that works with the first card to get a sum of 8)= P(card selected from Bowl X is 1, 2 or 3) x P(card selected from Bowl Y is the one card that works with the first card to get a sum of 8)= 3/4 x 1/5= 3/20